Highlighted weapons are free options.
Venti is a potent Off-Field DPS who can buff teammates through , or buff Anemo teammates through his Hexerei passive. With the addition of his Hexerei talents, he is no longer a Reaction-Based Off-Field DPS, although the playstyle is still utilized in some teams.
Make sure you don't immediately swap away after casting Burst; you need to be on-field for (4) perk to proc on Swirl first.( to avoid this issue).
You can infuse elements onto Venti's Burst if you walk into it with an elemental aura on you. (e.g. Bennett Burst > Venti Burst > Walk up to infuse Pyro)
Check out this link to see which characters can hit the enemies sucked and ragdolled in Venti's Burst.
Elemental Mastery can be used as an alternative Main Stat, however, it is less recommended.
For a Reaction-focused build, upgrading Venti's talent levels isn't a necessity.